A characteristic feature of the plasma membrane of prokaryotes is the prescence of what?

invaginated regions

Heterotrophs that harvest energy from organic molecules are called what?

chemoheterotrophs

Prokaryotes differ from eukaryotes in most characteristics besides what?

The plasma membrane

A microbiologist is investigating the effects of cold on a particular bacterium. He notices that as the temperature approaches zero degrees Centigrade, that the bacterium begins to

form endospores

Tuberculosis remains a serious world-wide health problem due to

1. Transmission through the air
2. Social factors such as crowding and poverty
3. The increasing prevalence of HIV infections
4. It is multi-drug resistant

A microbiologist is conducting a research project on chemoautotrophs. This means that the investigator is examining certain aspects of a bacterium that

can oxidize sulfur and other inorganic substances to get energy

The disease sometimes referred to as the "silent STD" because it is usually asymptomatic in women early on is

chlamydia

Chancre is a sore that is formed due to

nfection with Treponema pallidum

Most viruses form a capsid around their nucleic acid core. This capsid is composed of

a protein

Virulent viruses multiply within infected cells and eventually

cause lysis of the host cell, releasing new viruses

The genetic alteration of a cell’s genome by the introduction of foreign DNA is called

transformation

Recently a class of infectious proteins with no associated nucleic acid, have been identified. They are referred to as

prions

The HIV virus is considered a ______ virus, because after getting integrated into the host cell chromosomes, it does not begin replicating immediately.

latent

Each HIV particle possesses a ___________ on its surface that precisely fits a cell-surface marker protein called CD4 on the surfaces of the immune system cells called macrophages and T cells.

glycoprotein

Phages are viruses which can infect

bacteria

Viruses that become established as stable parts of the host cell genome are called

temperate

The infection cycle of HIV includes what steps?

attachment, entry into cells, replication, integration into the host cell's DNA, production of new viruses, and finally exit from the cells.

The onset of AIDS is often accompanied by

a steep drop in T cell numbers

A layer of lipoprotein and glycoprotein that covers the outer surface of some viruses is the

envelope

What are the major characteristics of viroids?

1. Naked RNA molecules
2. Only a few 100 nucleotides long
3. Important infectious diseases in plants

Question 13 text Scientists have demonstrated that the cholera bacteria, Vibrie cholerae, exist in at least two forms. It usually exists in a rather harmless form, however a phage conversion can occur which produces a disease-causing, virulent form. This conversion is caused by

the phage introducing a gene into the bacterium's chromosome that codes for the cholera toxin which can cause death in humans

Viruses infect every organism that has been investigated for their presence. However, viruses can only replicate in

a very limited number of the host’s cells

Viruses may cause cancer by

triggering the expression of cancer-causing genes present in the genome

The _________________________ viruses have been linked with liver cancer in people with chronic infections.

Hepatitis B and C

Located on or within the cell are _________ proteins, each of which has a three dimensional shape complementary to that of a specific signal molecule.

receptor

The space into which neurotransmitters are released is called a chemical

synapse

Cyclic AMP and calcium ions are often used within a cell as

secondary messengers

The cells of multicellular organisms use a variety of molecules as signals which are

The molecules that convert extracellular signals into intracellular ones are

cell surface receptors

Do chemically gated ion channels have genes incoded in them?

No

The class of cell surface receptors that act indirectly on plasma membrane-bound enzymes or ion channels are called

G proteins

A small number of surface receptors can ultimately generate a large intracellular response, as each step of the pathway is often expanded by

signal amplification

Most cells are in physical contact with other cells at all times by forming permanent connections called

cell junctions

In the digestive tract adjacent cells develop connections to form a sheet that prevents leakage of small molecules. These connections between cells are called

tight junctions

Small molecules or ions can pass from one cell to another through

communicating junctions

Junctions in which the cytoskeleton of a cell is attached to that of other cells or the extracellular matrix are called

anchoring junctions

A biochemist is designing a new drug that will mimic the shape of a particular signal molecule. She has to design the drug molecules so that they will be selected over the other “normal” molecules at the surface of the cell membrane. Therefore she must produce molecules that will bind to the receptor protein and

induce a change in the receptor molecule shape, which will ultimately produce a cellular response

What technique has recently aided the study of receptor proteins?

monoclonal antibodies

What occurs during autocrine signaling?

Signal molecules are released from a cell and bind to receptors on its own plasma membrane.